Professor Cliff Fleming has recently submitted his newest paper, A Note on the Zimmer Case and the Concept of Permanent Establishment, to SSRN.  This paper was published in Tax Treaty Case Law Around the Globe.  Here’s the abstract:

This paper argues that under Article 5(5) of the OECD Model Convention on Income and on Capital, foreign sellers are free to avoid permanent establishments in all source countries, regardless of whether a particular source country’s law includes the commissionaire concept, by selling through source country dependent agents that lack authority to enter into contracts that legally bind the foreign seller. This means that a foreign seller is substantially free to elect whether or not to have a permanent establishment in a source country.

More of Professor Fleming’s articles can be found on his SSRN page.